Key operated multiple switch



1960 s. A. WOODWARD 2,947,825

KEY OPERATED MULTIPLE SWITCH Filed Jan. 27, 1959 Z 2/ m /9 l 4 6 A? A1550 32 I 22 o a 34 n n W 2/ [fire/7f Ska/5M4 l'l wdwan/ W y z of j A05Aim/kg United tates Paten tlo 2,947,825 KEY OPERATED MULTIPLE SWITCHStewart A. Woodward, Stratford, Conn., assignor to General ElectricCompany, a corporation of New York Filed Jan. 27, 1959, Ser. No. 789,315'4 Claims. (Cl. 200) The present invention relates to electricalswitches and particularly to a multiple switch that is operated by asingle removable key for preventing the unauthorized operation of theswitch. Such a switch has many applications but is especially suited forcontrolling commercial air conditioning equipment in public places assupermarkets, theaters, and auditoriums. also be useful in home workshoppower equipment and as an outdoor control for garage door openers.

This switch is an outgrowth of the multiple push button switch designswhich were pioneered by the Andrews Patent No. 2,431,904 that isassigned to the same assignee as is the present invention. Key operatedtoggle switches have been used for many years but, to our knowledge,these are usually single switches that may be ganged together in asingle box. The present invention relates to a single switch forcontrolling multiple circuits where each circuit is arranged by theinsertion of a key in one of a plurality of openings in one wall of thehousing.

The principal object of this invention is to provide a multiple electricswitch for controlling a plurality of circuits where the switch actuatoris a removable key to render the switch tamperproof.

A further object of the present invention is to provide a multipleelectric switch with a restricting feature that will only accept aspecial key member. A still further object of this invention is toprovide a novel guiding means for a removable key that operates 'amultiple electric switch. a -"A preferred embodiment of the presentinvention has a plurality of fixed contacts and movable contact bladessupported in a switch housing. The blades are generally parallel to eachother and are operated by a plurality of movable sliders that arearranged transversely of the blades. One edge of each slider has a camsurface that cooperates with at least one of the contact blades so thatmovement of the sliders will control the opening and closing of thecircuits of the switch. The sliders also incorporate inclined portionswhich are formed by notching the opposite edge of the sliders. Theseinclined portions are engaged by a switch actuator for shifting thesliders in a predetermined manner. One wall of the housing has a seriesof narrow openings for the insertion of a removable key that representsthe switch actuator. The housing includes a guide plate with a matchingseries of narrow slots that are aligned with the openings in thehousing. Accordingly, as the key is inserted through an opening, it willextend into a cooperating slot in the guide plate so that the key isconfined to movement in a straight line direction. The before-mentionedsliders are arranged to the side of the guide plate so that the key willengage the inclined portions thereof and shift the sliders forrearranging the circuits of the switch.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

Figure l is a front view of a multiple electric switch embodying myinvention showing the removable key posed over one of the openings inthe top wall of the switch housing.

Figure 2 is a bottom plan view of the switch of Figure 1 with the coverplate removed to show the internal arrangement of the switch.

Figure 3 is a diagrammatic view showing the various movable sliders ofthe switch and the details thereof, as well as the novel guide platethat cooperates with the removable key.

Referring in detail to the drawing and in particular to Figures 1 and 2,there is shown a switch housing 10 formed by a recessed base 11 and abottom cover plate 12. With the back cover plate removed, it is possibleto look into the vase and identify the various elements of the switch,as is the case in Figure 2. The switch has The switch would a pluralityof fixed contacts 13 and a plurality of complementary movable contactblades 14 of spring material. All of these contacts have tab-typeterminals 15 which are fastened to the base as at 16 and extend throughclose-fitting apertures in the cover plate 12. The cover plate is heldto the base by deforming or staking the opposite sides of the terminalsas at 17.

The movable contact blades 14 are normally biased into engagement withthe fixed contacts. These blades 14 are acted upon by a plurality ofmovable sliders 18, 19, 20 and 21. These sliders are stamped from thinsheet insulating material and are usually of dissimilar shapes toperform the various functions of the switch mechanism. The sliders areaccommodated in a relatively deep channel 22 that is centrally disposedin the base 11 and extends longitudinally thereof. The side walls ofthis channel 22 confine the sliders to a stacked or side-by-siderelationship and serve to limit the move ment of the sliders to anendwise travel that is transverse of the movable contact blades 14.

The sliders are supported on the back cover plate 12. A series ofsupporting feet 23 are spaced longitudinally along one edge of eachslider for engaging the cover plate 12 without interfering with thecontact blades 14 as the sliders move within the base. Cam surfaces 24are provided between some of the supporting feet 23 of the sliders formaking engagement with a contact blade to force it to move away from thefixed contact and break the circuit. The opposite edge of each sliderhas a series of notches 25 with inclined portions 26 that are to beengaged by the switch actuator. I

Certain sliders, namely, sliders 18, 19 and 21 are provided with adetent action. This is accomplished by a plunger 27 that is backed by acoil spring 28. Both the plunger and spring are seated within thechannel 22 of the base. The plunger is in frictional engagement with thenotched edge of the sliders and cooperates with a curved abutment 29 oneach of the three sliders 18, 19 and 21. Accordingly, the detent spring28 must be compressed to allow the abutment 29 to slip under the plunger27 before any one of these three sliders can be shifted. v

The slider 20 is provided with a momentary contact action byincorporating a compression spring 30 at one end of the channel 22between the end wall of the base and the end of the slider '20. Hence,the normal-position of the slider 20 will be against the left-hand endwall 31 of the base as seen in Figure 2.

The actuator for this switch is represented by a removable key 32 ofthin metal strip. The strip is wide enough to be able to engage all ofthe sliders at one time. In other words, the width of the key is equalto or greater than the thickness of the stack of sliders. The top wallof the base 11 is provided with a series of narrow openings (not shown)so that the removable key 32 may be inserted into any one of them. Meansare provided'to limit the type of keythat may be used to operate thisswitch. Also, it is expedient to guide the movement of the key withinthe base as well as brace the key against forces exerted by the slidersthat might bend the key.

I I have chosen to satisfy these requirements by providing a guide plate34 that is stamped from sheet insulating material and has the generalappearance of a slider. However, this guide plate 34 differs from aslider in that it extends the complete length of the channel 22 and isincapable of moving lengthwise'of the base. This guide plate also hassupporting feet 23 as do the sliders, so that the cover plate 12 willhold it in place and the guide plate will not interfere with the contactblades 14. A series of narrow slots 35 are cut in the top edge of theguide plate to be in alignment with the narrow openings (not shown) inthe top wall of the base. These slots 35 are slightly narrower in widththan the openings in the base to restrict the type of key, instrument ortool which may be inserted into the switch housing by an unauthorizedperson attempting to circumvent the tarnperproof protection that isbuilt into this switch. A screwdriver could not be used to actuate theswitch because the blade of the screwdriver would either be too largefor both the opening in the base and the slot in the guide plate or theblade would be too narrow to engage all of the sliders. The same is trueof a nail. A knife blade could not be used because it has a pointed tipthat could not engage all of the sliders simultaneously. A hairpin wouldprobably be too weak to overcome the resistance of the detent spring 28and in some cases the additional force of the momentary contact spring30. The design of this switch almost requires an exact duplicate key tokey 32 in order to operate the switch. Attention is drawn to the contourof the notches 25 in the sliders and especially the innermost ends ofthe notches which are identified as 36. These innermost ends 36 conformvery closely to the configuration of the innermost ends of the slots 35of the guide plate, and the accurate positioning of the sliders is theresult.

Having described above my invention of a novel multiple switch having aremovable key actuator, it should be readily recognized by those skilledin this art that I have produced a simple design that is most practicaland economical to manufacture, assemble and operate. Also, I haveprovided against most of the common instrumentalities that might be athand to accomplish the unauthorized use of the switch. Anothermodification would be to install an OFF button in the switch so that itcould not be removed. This would always render it possible to turn ohthe switch in the event that the removable key 32 were lost orunavailable at the opportune moment. Moreover, it is conceivable thatdifferent types of keys and mating slots in the guide plate may be usedin place of the simple arrangement disclosed heretofore. Understandably,the guide plate could be an integral part of the housing rather than aseparable plate member. Modifications of this invention will occur tothose skilled in this art and it is to be understood, therefore, thatthis invention is not limited to the particular embodiments discolsedbut that it is intended to cover all modifications which are within thetrue spirit and scope of this invention as claimed.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

' '1. A multiple electrical switch comprising a housing,

plate.

a plurality of fixed contacts and movable contact blades supported inthe housing, each blade being engageable with at least one of the fixedcontacts for closing a circuit therethrough, a plurality of movablesliders arranged in the housing transversely of the contact blades, oneedge of the sliders having cam surfaces that cooperate with the contactblades'so that movement of the sliders will control the opening andclosing of the circuits through the switch, the sliders also havinginclined portions which are engaged by a switch actuator for shiftingthe sliders in a predetermined manner; the invention comprising a fixedguide plate within the housing, the plate having a series of narrowslots in one edge, one wall of the housing having a matching series ofnarrow openings in alignment with the slots, the switch actuator beingrepresented by a removable key that may be inserted into any one of theopenings for engaging the inclined portions of the sliders, the slots ofthe guide plate serving'to receive only the proper key and to seal theswitch from unauthorized operation.

2. A multiple electrical switch as recited in claim 1 wherein theinclined portions of the sliders are formed by notching the edge of eachslider that is remote from the cam surfaces, the innermost ends of thenotches being slotted to conform to the narrow width of the slots in theguide plate for accurately positioning the sliders within the housing.

3. A multiple switch as recited in claim 1 wherein the removable key hasa thin shank of uniform thickness which conforms very closely to thewidth of the openings in the housing and the width of the slots in theguide 4. A multiple electrical switch comprising a housing, a pluralityof fixed contacts and movable contact blades supported in the housing,each blade being engageable with at least one of the fixed contacts forclosing a circuit therethrough, a plurality of movable sliders arrangedin the housing, one edge of the sliders having cam surfaces thatcooperate with the contact blades so that movement of the sliders willcontrol the opening and closing of the circuits through the switch, thesliders also having inclined portions which are engaged by a switchactuator for shifting the sliders in a predetermined mannen'theinvention comprising a series of fixed guiding slots within the housing,the switch actuator being represented by a removable key, one wall ofthe housing having a series of openings so that the key may be insertedinto any one of the openings for engaging the inclined portions of thesliders, the guiding slots serving to block any instrue mentality butthe proper key from engaging and shifting the sliders, thereby sealingthe switch from unauthorized operation, the guiding slots also servingto brace the innermost end of the key that extends into the housing foraccurately positioning the sliders with respect to the contact blades.

References Cited in the file of this patent UNITED STATES PATENTS840,699 Kaish'ng Jan. 8, 1907 2,057,301 Golokow Oct. 13, 1936 2,376,846Field -----4----- May 22, 1945 2,819,356 Hutt Ian. 7, 1958 2,879,345Mossman Mar. 24, 1959

